A rectangular container measuring 70 cm by 56 cm by 22 cm was to be filled with water by two taps, P and Q. Tap P which fills the tank at a rate of 6 ℓ per minute was first turned on for 3 minutes before Tap Q was turned on as well. If the tank was filled to the brim in a total of 7 minutes from the time when Tap P was first turned on, what is the rate at which Tap Q fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 70 x 56 x 22
= 86240 cm
3 1 ℓ = 1000 cm
3 6 ℓ = 6000 cm
3 Volume of water filled by Tap P
= 6000 x 7
= 42000 cm
3 Volume of water filled by Tap Q
= 86240 - 42000
= 44240 cm
3 Rate in which Tap Q fills the container
= 44240 ÷ 4
= 11060 cm3/min
11060 mℓ/min
= 11.06 ℓ/min
≈ 11.1 ℓ/min (Correct to 1 decimal place)
Answer(s): 11.1 ℓ/min